Also verify that BarSigner.jar is present in the lib folder located in the parent folder of the bin folder. That's the jar that contains the class net.rim.device.codesigning.barsigner.BarSigner

[edit] Oh wait, you're on a Mac. That only means that you don't run barsigner.bat but it's Mac equivalent shell script. The same holds true, it cannot find BarSigner.jar at the expected location (being the "$here/../lib" folder)